update:更新自定义写作风格模块

backend/app/models/project_default_style.py

@@ -0,0 +1,23 @@
+"""项目默认风格关联表"""
+from sqlalchemy import Column, String, Integer, DateTime, ForeignKey, UniqueConstraint
+from sqlalchemy.sql import func
+from app.database import Base
+
+
+class ProjectDefaultStyle(Base):
+    """项目默认风格关联表 - 记录每个项目选择的默认风格"""
+    __tablename__ = "project_default_styles"
+    
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    project_id = Column(String(36), ForeignKey("projects.id", ondelete="CASCADE"), nullable=False, comment="项目ID")
+    style_id = Column(Integer, ForeignKey("writing_styles.id", ondelete="CASCADE"), nullable=False, comment="风格ID")
+    created_at = Column(DateTime, server_default=func.now(), comment="创建时间")
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now(), comment="更新时间")
+    
+    # 确保每个项目只有一个默认风格
+    __table_args__ = (
+        UniqueConstraint('project_id', name='uix_project_default_style'),
+    )
+    
+    def __repr__(self):
+        return f"<ProjectDefaultStyle(project_id={self.project_id}, style_id={self.style_id})>"